Flexible containers are commonly used for containment and delivery of medical fluids. These containers are generally single use bags manufactured from one or more types of plastic film that can be irradiated or otherwise withstand sterilization such that the container can be rendered aseptic. The containers are often used in life science applications and in the manufacture of pharmaceuticals to contain liquid raw materials prior to or during manufacture; in other cases such containers may be used to contain the finished product. The contents of these containers may be precious, particularly when used in large scale production. It is not unusual for even small containers to contain material worth many thousands of dollars.
Accordingly, it is beneficial to try to determine in advance whether the container may have an abnormality that might result in a rupture or other failure of the container that could lead to a loss of its contents.
One common solution employed for testing container integrity is to partially fill the container with helium, the container being placed within an enclosure along with a sensor able to detect the presence of helium. If helium is detected, a determination can be made whether there are any pores or pin holes not readily observable through which the helium is escaping.
Among the drawbacks to this methodology is that helium testers are generally large in size and expensive to operate. These systems require a ready source of helium that adds further expense and that also limits the available locations within a facility where that testing can take place. Furthermore, helium testing requires that the container be restrained, which requires additional valuable technician time. Yet another drawback is that silicon and other materials sometimes used in the manufacture of flexible containers are permeable to helium, making leak detection difficult and increasing the likelihood of false positives and the chance that a satisfactory bag will be needlessly discarded.
Even in situations where the container has no flaws from manufacture, they are shipped in a deflated or even evacuated state for convenience in shipping and storage. As the containers are filled, they expand as a result of the incoming fluid being pumped into the container. Filling is typically an automated process set to pump a pre-determined volume of fluid corresponding to the size of the container. However, the nature of the plastic used to form the containers is such that crinkles or other areas of self-adhesion may have developed during folding. This can result in a net decrease in the total volume of the container available for storage compared to the manufactured volume.
In many industrial settings, the containers may have a volume of several hundred or even a thousand or more liters. Thus, the weight of the container during filling can quickly become so heavy that manual manipulation to eliminate crinkles is impractical or impossible. In severe cases, the reduction in volume may be such that the volume of the liquid being pumped into the container exceeds the available container volume as a result of the crinkles to the point that the elasticity of the plastic is exceeded and the container bursts.
These and other disadvantages are found in known systems and methods for testing the integrity of flexible containers.